High-sensitivity stable-isotope probing by a quantitative terminal restriction fragment length polymorphism protocol

Area of Science:

• Microbial Ecology
• Molecular Biology
• Environmental Science

Background:

• Stable-isotope probing (SIP) is a key cultivation-independent technique for linking microbial taxa to functions.
• Standard SIP methods face resolution limitations with microbial groups exhibiting minor buoyant density shifts, such as those utilizing specific nitrogen sources.

Purpose of the Study:

• To develop an improved SIP method for enhanced resolution of microbial populations with minor buoyant density shifts.
• To quantify specific microbial taxa within gradient fractions obtained during SIP experiments.

Main Methods:

• Development of a tandem quantitative PCR (qPCR)-TRFLP protocol.
• Utilized FAM-labeled PCR products and EvaGreen dye for amplification monitoring.
• Validated the method using cloned 16S rRNA genes, diverse bacterial isolates, and soil microcosms.

Main Results:

• The qPCR-TRFLP protocol significantly improved the resolution of labeled microbial populations compared to TRFLP alone.
• Accurate quantification of specific taxonomic groups was achieved in gradient fractions.
• Demonstrated improved detection of minor buoyant density shifts in microbial communities.

Conclusions:

• The developed tandem qPCR-TRFLP method offers enhanced resolution for SIP studies.
• This technique is valuable for accurately identifying and quantifying microbial populations with subtle density changes, advancing functional microbial ecology research.